Dummett made three appearances for Collingwood in the 1909 VFL season, as an 18 year old. He didn't feature at all in 1910, when Collingwood went on to claim the premiership. In 1911 he played just one senior game. His brother, Alf Dummett, was also at Collingwood in these years but they never got the opportunity to play together.

From 1927 to 1945, Dummett goal umpired 264 VFL matches, the most ever by a former player. He officiated in the 1933 and 1943 VFL Grand Finals.